Which of the Following Would Be the Best Way to Determine

Multiple Choice

Which of the following would be the best way to determine if aphids must actively draw phloem sap into their digestive tract or if hydrostatic pressure in the phloem tube could force the sap into them?

A) Cut a phloem tube off an aphid and see if it can still feed.
B) Cut a phloem tube from a plant and see if an aphid can still take up sap from it.
C) Measure relative rates of sugar manufacture in leaves with and without aphids.
D) Insert mouth parts removed from an aphid, without including the digestive tract, into phloem sap and see if sap keeps flowing through them.